A nonaqueous electrolyte battery represented by a lithium ion secondary battery has a high energy density. From this reason, a nonaqueous electrolyte secondary battery is used in various fields from small portable devices such as a personal computer and a smart phone to large electric power sources including an electric vehicle and a power-leveling power source.
Accompanying with the increase in power consumption of an apparatus using a nonaqueous electrolyte battery and the expansion of fields for which a nonaqueous electrolyte battery is used, it has been studied to improve large current characteristics and low-temperature characteristics.
In order to improve the large current characteristics and the low-temperature characteristics of a nonaqueous electrolyte battery, it is effective to improve electroconductivity and lithium ion conductivity. In order to improve electroconductivity, it is effective to increase the amount of an electroconductive material in a positive electrode active material layer and/or a negative electrode active material layer and to decrease the thickness of an active material layer. Also, in order to improve lithium ion conductivity, it is effective to decrease the viscosity of an electrolyte solution and to increase the concentration of a lithium ion in an electrolyte solution.
However, the increase in the amount of an electroconductive material in an active material layer and the decrease in the thickness of an active material layer cause the decrease in the energy density of a nonaqueous electrolyte battery. Also, the decrease in the viscosity of an electrolyte solution causes the deterioration of high-temperature characteristics. Also, the increase in the concentration of a lithium ion in an electrolyte solution causes the deterioration of low-temperature characteristics.
Therefore, in a conventional nonaqueous electrolyte battery, large current characteristics and low-temperature characteristics may not be sufficiently obtained.